Airworthiness Directive · Amendment 39-16374 · Wings
The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes
Superseded. A later AD replaced this one: AD 2014-05-12. Comply with the one in force.
This AD applies to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.
The FAA is superseding an existing airworthiness directive (AD), which applies to all Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That AD currently requires repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps, and corrective action if necessary. That AD also currently requires repetitive gap checks of the inboard and outboard carriage of the outboard mid-flaps to detect fractured carriage spindles, and corrective actions if necessary. This new AD requires any new or serviceable carriage spindle installed per the requirements of the existing AD to meet minimum allowable diameter measurements taken at three locations. This AD also requires new repetitive inspections, measurements, and overhaul of the carriage spindles, and applicable corrective actions. In addition, this AD requires replacing any carriage spindle when it has reached its maximum life limit. This AD results from reports of fractures that resulted from stress corrosion and pitting along the length of the spindle and spindle diameter, and additional reports of corrosion on the outboard flap carriage spindles. We are issuing this AD to detect and correct cracked, corroded, or fractured carriage spindles, and to prevent severe flap asymmetry, which could result in reduced control or loss of controllability of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
The tables in paragraph 1.E., “Compliance” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003, specify the compliance times for paragraphs (g) through (k) of this AD. For carriage spindles that have accumulated the number of flight cycles or years in service specified in the “Threshold” column of the tables, accomplish the gap check and nondestructive test (NDT) and general visual inspections specified in paragraphs (h) and (j) of this AD within the corresponding interval after December 4, 2003 (the effective date AD 2003-24-08), as specified in the “Interval” column. Repeat the gap check and NDT and general visual inspections at the same intervals, except:
(1) The gap check does not have to be done at the same time as an NDT inspection; after doing an NDT inspection, the interval for doing the next gap check can be measured from the NDT inspection; and
(2) As carriage spindles gain flight cycles or years in service and move from one category in the “Threshold” column to another, they are subject to the repetitive inspection intervals corresponding to the new threshold category.
Perform a gap check of the inboard and outboard carriage of the left and right outboard mid-flaps to determine if there is a positive indication of a severed carriage spindle, in accordance with Work Package 2 of paragraph 3.B., “Work Instructions” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003.
(i) If there is a positive indication of a severed carriage spindle during the gap check required by paragraph (h) of this AD, before further flight, remove the carriage spindle and install a new or serviceable carriage spindle in accordance with the “Work Instructions” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003; or Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. If, as a result of the detailed inspection described in paragraph 4.b. of Work Package 2 of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003, a carriage spindle is found not to be severed and no corrosion and no cracking is present, it can be reinstalled on the mid-flap in accordance with Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003; or Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. After the effective date of this AD, use only Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009.
Perform a NDT inspection and general visual inspection for each carriage spindle of the left and right outboard mid-flaps to detect cracks, corrosion, or severed carriage spindles, in accordance with the “Work Instructions” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003.
If any corroded, cracked, or severed carriage spindle is found during any inspection required by paragraph (j) of this AD, before further flight, remove the carriage spindle and install a new or serviceable carriage spindle in accordance with the “Work Instructions” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003; or Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. After the effective date of this AD, use only Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009.
Except as provided in paragraph (i) of this AD: As of December 4, 2003, no person may install on any airplane a carriage spindle that has been removed as required by paragraph (i) or (k) of this AD, unless it has been overhauled in accordance with the “Work Instructions” of Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003; or Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. After the effective date of this AD, use only Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. To be eligible for installation under this paragraph, the carriage spindle must have been overhauled in accordance with the requirements of paragraph (m) of this AD.
(m) During accomplishment of any overhaul specified in paragraph (l) of this AD, use the procedures specified in paragraphs (m)(1) and (m)(2) of this AD during application of the nickel plating to the carriage spindle in addition to those specified in Chapter 20-42-09, Electrodeposited Nickel Plating, of the Boeing (737) Standard Overhaul Practices Manual. As of the effective date of this AD, use only Chapter 20-42-09, Electrodeposited Nickel Plating, of the Boeing (737) Standard Overhaul Practices Manual, Revision 25, dated July 1, 2009.
(1) The maximum deposition rate of the nickel plating in any one plating/baking cycle must not exceed 0.002-inches-per-hour.
(2) Begin the hydrogen embrittlement relief bake within 10 hours after application of the plating, or less than 24 hours after the current was first applied to the part, whichever is first.
Although Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003, recommends that operators report inspection findings to the manufacturer, this AD does not contain such a reporting requirement.
At the applicable times specified in paragraph (o)(1) or (o)(2) of this AD: Do the detailed inspection for corrosion, pitting, and cracking of the carriage spindle, the magnetic particle inspection for cracking of the carriage spindle, measurements of the spindle to determine if it meets the allowable minimum diameter, and overhauls, and applicable corrective actions by accomplishing all the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009. The applicable corrective actions must be done before further flight. Repeat these actions thereafter at intervals not to exceed 12,000 flight cycles on the carriage spindle or 8 years, whichever comes first.
(1) For Model 737-100, -200, -200C series airplanes, at the later of the times specified in paragraph (o)(1)(i) or (o)(1)(ii) of this AD:
(i) Before the accumulation of 12,000 total flight cycles on the carriage spindle since new or overhauled, or within 8 years after the installation of the new or overhauled part, whichever comes first.
(ii) Within 1 year after the effective date of this AD.
(2) For Model -300, -400, and -500 series airplanes, at the later of the times specified in paragraph (o)(2)(i) or (o)(2)(ii) of this AD:
(i) Before the accumulation of 12,000 total flight cycles on the carriage spindle since new or overhauled, or within 8 years after the installation of the new or overhauled part, whichever comes first.
(ii) Within 2 years after the effective date of this AD.
For Model 737-100, -200, -200C series airplanes: Replace the carriage spindle with a new or documented (for which the service life, in total flight cycles, is known) carriage spindle, in accordance with Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009, at the later of the times specified in paragraphs (p)(1) and (p)(2) of this AD, except as required by paragraph (r) of this AD. Overhauling the carriage spindles does not zero-out the flight cycles. Total flight cycles accumulate since new.
(1) Before the accumulation of 48,000 total flight cycles on the new or overhauled carriage.
(2) Within three years or 7,500 flight cycles after the effective date of this AD, whichever occurs first.
(q) For Model 737-300, -400, and -500 series airplanes: Replace the carriage spindle with a new or documented (for which the service life, in flight cycles, is known) carriage spindle, in accordance with Boeing Alert Service Bulletin 737-57A1218, Revision 5, dated February 9, 2009, at the later of the times specified in paragraphs (q)(1) and (q)(2) of this AD, except as required by paragraph (r) of this AD. Overhauling the carriage spindles does not zero-out the flight cycles. Total flight cycles accumulate since new.
(1) Before the accumulation of 48,000 total flight cycles on the new or overhauled carriage.
(2) Within six years or 15,000 flight cycles after the effective date of this AD, whichever occurs first.
(r) For airplanes with an undocumented carriage: Do the applicable actions specified in paragraph (p) or (q) of this AD at the applicable time specified in paragraph (r)(1) or (r)(2) of this AD.
(1) For Model 737-100, -200, -200C series airplanes: Do the actions specified in paragraph (p) of this AD at the time specified in paragraph (p)(2) of this AD.
(2) For Model -300, -400, and -500 series airplanes: Do the actions specified in paragraph (q) of this AD at the time specified in paragraph (q)(2) of this AD.
For all airplanes: Repeat the replacement of the carriage spindle specified by paragraph (p) or (q) of this AD, as applicable, thereafter at intervals not to exceed 48,000 total flight cycles on the new or overhauled carriage spindle.
